-LRB- CNN -RRB- -- Government troops fought fresh battles with opposition fighters in Yemen 's capital , Sanaa , early Friday as the country 's embattled president tried to put down a tribal revolt .

Troops backed by tanks were nearing the home of tribal leader Sadeq Al-Ahmar , whose followers have been battling troops loyal to President Ali Abdullah Saleh for nearly two weeks , witnesses reported . The nearby headquarters of Yemen 's national airline was ablaze , with surrounding houses catching fire as well , witnesses said .

Government spokesman Abdu Ganadi told CNN said Saleh 's forces `` are near victory . '' But Abdulqawi Al-Qaisi , a spokesman for Al-Ahmar , said `` All government claims of victory are fabricated , and our forces are still on the ground . ''

And in Change Square , where tens of thousands of anti-government protesters have made camp , witnesses said gunmen on surrounding streets were firing into the crowd , while snipers were visible on nearby rooftops .

`` It 's very tense inside Change Square now , because there is a fear that government forces might attempt to come into Change Square and take it over at any time , '' one of the protesters , who asked to remain anonymous due to security concerns , told CNN . A nearby resident said the fighting had subsided after midnight , however .

`` We 're still hearing bombs and gunfire , but not as much as we were just an hour ago , '' the resident said .

The fighting erupted May 23 , after Saleh balked at a deal negotiated by Persian Gulf states that would have eased him from office in 30 days . The intensity of the fighting in the capital , where most of Yemen 's security forces and army units are based , has increased fears that the country is on the verge of civil war .

Saleh has ruled Yemen since 1978 , and the nation has been a key U.S. ally in the battle against the al Qaeda terrorist network . But Yemen was caught up in the wave of protests that swept the Arab world after the January ouster of Tunisia 's longtime strongman , leaving Saleh battling both peaceful and violent resistance movements .

The impoverished , arid and mountainous nation has a weak central government and contains vast stretches where tribal law reigns supreme . A fresh group of about 1,000 armed tribesmen were seen entering Sanaa early Thursday , Sanaa resident Nageeb Mujaili said .

`` We asked them why they were going to Sanaa armed , '' said Mujaili . `` And they said to support their leader , Sheikh Sadeq Al-Ahmar . ''

Yemeni state television reported that government forces had beaten back tribal fighters from areas of the capital near the Ministry of Tourism building on Thursday , and Sanaa residents reported hearing explosions near the presidential palace , a government source said .

`` The reason the street fighting in Sanaa has gotten a lot more intense in the past several hours is because special forces are now involved , '' said the source , who asked not to be identified because he is not authorized to speak to the news media .

`` The special forces of the Republican Guard , the elite units , got involved on Wednesday . They 're being used because the government wants to minimize collateral damage and the special forces have particular training in clearing fighters from buildings . ''

A security official at Sanaa International Airport said inbound and outbound flights were halted due because of security concerns over clashes near the airport . But the official , who is not authorized to speak to the media , said that the airport itself is not closed .

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NEW : New fighting reported near the home of the leader of a tribal revolt

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NEW : Protesters fired on in Change Square , witnesses report

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NEW : The headquarters of Yemen 's national airline has been set ablaze , witnesses say

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NEW : A government spokesman says victory is near ; tribal official dismisses the claim